The vulcanized rubber pneumatic tire has proved to be both a blessing and a curse to modern society. We can't live without tires and we are just beginning to realize we can't live with millions of worn out tire carcasses clogging our landfills and littering our environment. Tires are particularly villainous at prematurely filling dump sites because their hollow toroidal shape is particularly volume consuming and they do not easily compress or nest within one another. About the only way anybody ever has gotten rid of a used tire has been to burn it. This solution has been so unsatisfactory that it is now illegal in most jurisdictions. Burning tires cause a horrible stench and pollute the air with toxic fumes and particles harmful to all life forms. Even expensive modern incineration devices, complete with scrubbers for the exhaust fumes, are inferior at destroying old tires. The steel belting materials clog the incinerator while the particulate carbon and sulfur compounds tends to foul the scrubbers. Additionally, many incineration devices consume electrical energy which serves primarily to transfer the pollution down the river to where the energy is being produced.
The difficulty in discarding worn out tires and the energy and raw materials required to manufacture them has inspired much effort to refurbish them for further use by retreading. These efforts have spawned entire industries presently listed on the New York Stock Exchange. However, there are several major problems with producing retreads. The new tread which is to be bonded to the old tire must be produced somewhere. Extensive amounts of energy are used in to produce the heat required to bond the new tread to the old tire and, even then, that crucial bonding is not always well accomplished. Both the bonding and the production of a new tread surface are, in many respects, just further examples of shipping the pollution down the river. All told, there is probably as much energy used in pollution produced in the manufacture of a retreaded tire as in the production of the original tire. Here, as incineration, the steel belts and cords used in modern tires pose severe obstacles to the successful completion of the process. Not all tires can be effectively recycled by the retreading process. For example, if the sidewall or sealing bead is damaged there is no good means to reclaim that tire. The problem here is that a tire must not only have sufficient tread but must also meet stringent standards of flexibility, strength, air permeability, and appearance.
A second alternative of somehow reforming the old tire carcass into other useful articles has been pursued by others with generally limited success. It has been proposed that old tires could be shredded and used as a form of insulation material perhaps mixed with other insulation materials such as vermiculite. This proposal does indeed recognize the important property of extremely low thermal conductivity. The actual shredding process would be extremely difficult especially when steel belts are imbedded in the old tires. Even if the metal were successfully minced up with the rubber it would have to be separated later because it would seriously degrade the thermal insulation properties of the final product. Also, the actual volume of shredded material recovered in this manner would be relatively small with respect to the volume of the original tire carcasses. You would need a mountain of old tires to produce a truckload of shredded rubber insulation material and that truckload might be enough to insulate one house. These relative quantities are, of course, not meant to be precise but merely to point out the fact that there are problems of scale involved with shredding tire carcasses to produce a voluminous product such as household insulation.
Following along with the idea of making some sort of useful product out of the old tire carcasses, there have been numerous proposals to create all kinds of decorative and ornamental articles from the tires. Examples of such uses are flower planters and landscape dividers. Two other applications of limited but useful merit will be familiar to all. Anyone from a farm or rural community will have seen a tire hung from a rope to form the familiar "tire swing". Anyone living on or near a body of water will have seen old tires attached to the sides of docks for cushioning the impacts of boats. This particular use highlights the important and useful impact absorption properties of the tire material. It has been recorded in the magazine "ABC-American Roofer and Building Improvement Contractor", February, 1978, that old truck tires have been flattened and used as a form of roofing. They are overlapped in an alternating tread-out tread-in pattern to form a watertight seal for this purpose.
Numerous United States Patents have been granted for various and sundry articles made from old tires. The largest group of these Patents are concerned with providing highway safety dividers or barriers thus effectively utilizing the inherent impact energy absorption characteristics of the rubber. Bruner et al, U.S. Pat. No. 4,186,913, shows an arrangement of side by side upright tire casings supported in a solid rubber block which is poured around the lower portions of the tires. Bruner also mentions the possible use of this arrangement as a breakwater. Ward, U.S. Pat. No. 4,030,706, shows a highway bumper guard made from two tire casings arranged concentrically within one another and with the inner casing being filled with particulate material such as sand. Ward recognizes that this arrangement will absorb impact energy by virtue of the friction between the concentric tires. As will be seen later, this type of internal friction can also be an important feature of my invention. Yoho, U.S. Pat. No. 4,066,244, shows an arrangement of upright tire casing connected together in transverse lines and rows for the purpose of absorbing impact energy. Schaaf et al, U.S. Pat. No. 4,312,600, discloses a traffic barricade or marker whose base is formed from a horizontal tire casing. Schaaf recognizes that the interior portion of the tire casing may be filled with a buoyant material thus forming a buoy marker.
Other miscellaneous exploitations of used tire casing are shown by Doring, U.S. Pat. No. 4,142,821 and by Moore, U.S. Pat. No. 4,022,434. Doring shows ground stabilization devices for embankments, etc. made from variously interconnected loops of tire treads with the sidewalls removed. Moore shows a means of stacking and interconnecting upright tires to form a fence. The tire fence is supported by partially burying the lower course of tires. Moore recognizes yet another important property of the tire material, low electrical conductivity. Moore exploits this property by stringing electrified barbed wire directly from his fence without the need for expensive electrical insulator offset devices of any kind. As will be seen later, this is another property which enhances to the overall desirability of my invention.
The many and varied previous uses for old tire casings serve to illustrate and take advantage of the important property of chemical inertness. Tire casing material will not rot, decay, decompose, deteriorate, or easily disintegrate. Tire casings are impervious to attack from mold, fungus, or bacteria, or other microorganisms. Insects, rodents, birds, bats, deer, barnacles, and other animals can not destroy tire casings. Corrosive agents, such as salt water and most acids, do not harm tire casings. Prolonged exposure to ultra-violet radiation does not degrade tire casing material. Tire material will withstand extreme climatic temperature ranges without substantial deterioration of its excellent strength and toughness characteristics.
In spite of the many and varied uses for old tire casings proposed by the prior art, it is well known that old tires are most often discarded in garbage dumps where they often collect stagnant water and serve as breeding grounds for mosquitoes and other pests. My invention proposes a new product, made from those old tires, whose usefulness is so general and application so broad that old tires will no longer need to be discarded.